Evidence of increased keratinocyte proliferation in air-liquid interface cultures of non-bullous congenital ichthyosiform erythroderma
Amsellem, C.; Haftek, M.; Hoyo, E.; Thivolet, J.; Schmitt, D.
Acta Dermato-Venereologica 73(4): 262-269
1993
ISSN/ISBN: 0001-5555 PMID: 7506468 Document Number: 419173
Modern pharmacological and dermatological research requires the use of appropriate in vitro models which permit a faithful reproduction of various aspects of the in situ situation. The air-exposed culture of keratinocytes on dead de-epidermized dermis is one of the best models of in vitro epidermal differentiation known at the moment. In this study, we verified the model's validity for the reproduction of a hyperproliferative genodermatosis: non-bullous congenital ichthyosiform erythroderma. We used subcultured epidermal keratinocytes originating from normal and ichthyotic patients. Light and electron microscopy of pathological cultures disclosed, on day 14, a terminally differentiated epidermis with a marked granular layer and hyperkeratosis which, however, was not dramatically different from the normal controls. On day 25, the normal cultures displayed an even more pronounced hyperkeratosis and hypergranulosis, whereas the reconstructed epidermis of pathological origin presented a considerable reduction of the viable non-keratinized compartment and a focal parakeratosis. Indirect immunofluorescence revealed the expression of several differentiation markers which were not observed in the immersed culture models (e.g. the desmosome- and differentiation-related antigens KM48 and G36-19). Abundant keratohyalin granules were stained with AKH1 antibody and observed even in - the deep epidermal layers, but no profilaggrin-filaggrin conversion could be detected biochemically. The cultures displayed some hyperproliferative features, as judged by KL1 and anti-involucrin antibody stainings. The keratinocyte proliferation was estimated by three different methods: 1) the rate of bromodeoxyuridine incorporation, 2) the expression of proliferating cell nuclear antigen and 3) the argyrophilic nucleolar organizer region counts. lt proved to be more elevated in additional striking and statistically significant difference was observed all cultures when compared to the normal skin biopsies. An additional striking and statistically significant difference was observed between the normal and ichthyotic cultures on day 14 but was no longer detected after 25 days of culture. Our findings demonstrate that keratinocyte hyperproliferation, a major marker of the ichthyotic epidermis, is maintained in vitro in the emerged culture conditions, even though this model shows a baseline tendency for hyperproliferation.